1. The Field of the Invention
The present invention broadly relates to novel surfactant compositions and a method of washing soiled substrates therewith. In some of its more specific variants, the invention is concerned with acidic liquid surfactant compositions and the use thereof in washing textile materials and soiled substrates in general.
2. The Prior Art
Concentrated liquid synthetic detergents possess a number of advantages which are attractive from the standpoints of convenience and efficiency. This is especially true when operating modern institutional laundry equipment of the type wherein bulk liquid washing chemicals are stored in auxiliary tanks and added automatically to the washer through feed conduits at predetermined stages in the washing cycle. In some instances, the concentrated liquid detergent is added directly to the washer, and in other instances it is diluted with water to form a stock solution which is then added.
A commercially successful liquid detergent composition for sale to the institutional laundry industry should possess a combination of desirable properties. The liquid detergent should be concentrated to reduce shipping and storage costs. It should also be homogeneous, stable, and sufficiently fluid and mobile to flow easily through the detergent feed conduit. A solid precipitate, gel, or other nonhomogeneous phase should not form therein during storage or use, nor should deposits form on the internal surfaces of the detergent storage tank and feed conduits. The concentrated detergent should be easily diluted with water prior to use and/or capable of being added directly to the wash water without adverse effects. The composition should give good detergency values in soft water and preferably also in hard water, and it should not require an expensive additive which increases costs without increasing the detergency value such as a hydrotrope or perfume. It is also essential from the pollution control standpoint that the detergent be biodegradable in order to meet the requirements of pollution control laws.
Alkyl benzene sulfonic acid detergents in the free acid or salt form are widely used at the present time and several prior art liquid detergent compositions have been proposed which are prepared therefrom. However, the resulting compositions are deficient in one or more of the above mentioned desirable properties. A number are not biodegradable nor concentrated. When concentrated, the compositions contain an expensive hydrotrope which has little or no detergency value and yet is essential in preparing and maintaining a homogeneous stable solution of the ingredients. Some of the concentrated acidic detergent compositions are not fully compatible with alkaline wash water and thus should not be added directly to the washer, or they require agitation and/or heating at the time of diluting to produce a stock solution which then may be added to the water. Still other of the aforesaid detergent compositions are adversely affected by hard water and/or do not give outstanding detergency values for other reasons, and perfumes or other expensive ingredients are required for esthetic purposes. Accordingly, the art has long sought an entirely satisfactory liquid composition containing an alkyl benzene sulfonic acid which overcomes the aforementioned deficiencies and which possesses the desirable properties mentioned hereinbefore to an unusual degree.